Phenytoin toxicity has been seen in some patients given
fluconazole or
miconazole.
Phenytoin may reduce
fluconazole levels. Fosphenytoin, a prodrug of
phenytoin, may interact similarly.
Toxicity can develop within 2 to 7 days. Monitor
serum phenytoin levels closely and reduce the dosage appropriately. Also be alert for any evidence of reduced antifungal effects and consider increasing the dose. Note that, at high doses,
miconazole oral gel has the potential to interact.